Top quarks in the Large Hadron Collider (LHC) proton-proton collisions are predominantly produced in pairs, with one top quark and one top antiquark. In order to measure the production rates of top quark pairs, the ATLAS Experiment examined events with an electron, muon, and one or two jets that were likely to have originated from bottom quarks. By comparing the number of events with one bottom-quark jet to those with two bottom-quark jets, ATLAS was able to determine both the total production rate, as well as the efficiency of identifying bottom-flavoured jets.